It is important for at least navigational purposes for a moving or movable vehicle to know its heading and/or pitch. In the case of a ship at sea, there may be situations in which the ship is lost and there are no landmarks in sight. In a battle zone, there may be situations in which a ship at sea has damaged heading and/or attitude sensors, or in which the sensors are severely degraded due to man-made or natural anomalies. For example, it is well known that the earth's electromagnetic magnetic field has an extreme effect on magnetic sensors as a ship approaches the earth's poles.
Improved or alternative arrangements are desired for heading and/or pitch determinations.